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<h1>timer_isr.c</h1><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">/*********************************************************************************</span>
<a name="l00002"></a>00002 <span class="comment"></span>
<a name="l00003"></a>00003 <span class="comment"> Copyright 2006 MakingThings</span>
<a name="l00004"></a>00004 <span class="comment"></span>
<a name="l00005"></a>00005 <span class="comment"> Licensed under the Apache License, </span>
<a name="l00006"></a>00006 <span class="comment"> Version 2.0 (the "License"); you may not use this file except in compliance </span>
<a name="l00007"></a>00007 <span class="comment"> with the License. You may obtain a copy of the License at</span>
<a name="l00008"></a>00008 <span class="comment"></span>
<a name="l00009"></a>00009 <span class="comment"> http://www.apache.org/licenses/LICENSE-2.0 </span>
<a name="l00010"></a>00010 <span class="comment"> </span>
<a name="l00011"></a>00011 <span class="comment"> Unless required by applicable law or agreed to in writing, software distributed</span>
<a name="l00012"></a>00012 <span class="comment"> under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR</span>
<a name="l00013"></a>00013 <span class="comment"> CONDITIONS OF ANY KIND, either express or implied. See the License for</span>
<a name="l00014"></a>00014 <span class="comment"> the specific language governing permissions and limitations under the License.</span>
<a name="l00015"></a>00015 <span class="comment"></span>
<a name="l00016"></a>00016 <span class="comment">*********************************************************************************/</span>
<a name="l00017"></a>00017 
<a name="l00018"></a>00018 <span class="comment">/* </span>
<a name="l00019"></a>00019 <span class="comment">  BASIC INTERRUPT DRIVEN DRIVER FOR MAKE BOARD. </span>
<a name="l00020"></a>00020 <span class="comment">*/</span>
<a name="l00021"></a>00021 
<a name="l00022"></a>00022 <span class="comment">/* Scheduler includes. */</span>
<a name="l00023"></a>00023 
<a name="l00024"></a>00024 <span class="preprocessor">#include "FreeRTOS.h"</span>
<a name="l00025"></a>00025 
<a name="l00026"></a>00026 <span class="preprocessor">#include "types.h"</span>
<a name="l00027"></a>00027 
<a name="l00028"></a>00028 <span class="preprocessor">#include "timer.h"</span>
<a name="l00029"></a>00029 <span class="preprocessor">#include "timer_internal.h"</span>
<a name="l00030"></a>00030 
<a name="l00031"></a>00031 <span class="preprocessor">#include "io.h"</span>
<a name="l00032"></a>00032 
<a name="l00033"></a>00033 <span class="preprocessor">#include "AT91SAM7X256.h"</span>
<a name="l00034"></a>00034 
<a name="l00035"></a>00035 <span class="keyword">extern</span> <span class="keyword">struct </span>Timer_ Timer;
<a name="l00036"></a>00036 
<a name="l00037"></a>00037 <span class="comment">// At the moment, the Timer ISR or callbacks, very importantly, can't call any OS stuff since</span>
<a name="l00038"></a>00038 <span class="comment">// the IRQ might happen any old where</span>
<a name="l00039"></a>00039 
<a name="l00040"></a>00040 <span class="keywordtype">void</span> Timer_Isr( <span class="keywordtype">void</span> ) __attribute__ ((interrupt("IRQ")));
<a name="l00041"></a>00041 <span class="comment">//void Timer_Isr( void ) __attribute__ ((interrupt(naked)));</span>
<a name="l00042"></a>00042 
<a name="l00043"></a>00043 <span class="keywordtype">void</span> Timer_Isr( <span class="keywordtype">void</span> )
<a name="l00044"></a>00044 {
<a name="l00045"></a>00045   <span class="comment">/* This ISR can cause a context switch.  Therefore a call to the </span>
<a name="l00046"></a>00046 <span class="comment">  portENTER_SWITCHING_ISR() macro is made.  This must come BEFORE any </span>
<a name="l00047"></a>00047 <span class="comment">  stack variable declarations. */</span>
<a name="l00048"></a>00048   <span class="comment">// portENTER_SWITCHING_ISR();</span>
<a name="l00049"></a>00049 
<a name="l00050"></a>00050   <span class="keywordtype">int</span> status = AT91C_BASE_TC0-&gt;TC_SR;
<a name="l00051"></a>00051   <span class="keywordflow">if</span> ( status &amp; AT91C_TC_CPCS )
<a name="l00052"></a>00052   {
<a name="l00053"></a>00053     Timer.servicing = <span class="keyword">true</span>;
<a name="l00054"></a>00054 
<a name="l00055"></a>00055     <span class="keywordtype">int</span> jitter;
<a name="l00056"></a>00056     Timer.count++;
<a name="l00057"></a>00057     jitter = AT91C_BASE_TC0-&gt;TC_CV;
<a name="l00058"></a>00058 
<a name="l00059"></a>00059     Timer.jitterTotal += jitter;
<a name="l00060"></a>00060     <span class="keywordflow">if</span> ( jitter &gt; Timer.jitterMax )
<a name="l00061"></a>00061       Timer.jitterMax = jitter;
<a name="l00062"></a>00062     <span class="keywordflow">if</span> ( jitter &gt; Timer.jitterMaxAllDay )
<a name="l00063"></a>00063       Timer.jitterMaxAllDay = jitter;
<a name="l00064"></a>00064 
<a name="l00065"></a>00065     <span class="comment">// Run through once to make the callback calls</span>
<a name="l00066"></a>00066     TimerEntry* te = Timer.first;
<a name="l00067"></a>00067     Timer.next = NULL;
<a name="l00068"></a>00068     Timer.previous = NULL;
<a name="l00069"></a>00069     Timer.nextTime = -1;
<a name="l00070"></a>00070     <span class="keywordflow">while</span> ( te != NULL )
<a name="l00071"></a>00071     {
<a name="l00072"></a>00072       Timer.next = te-&gt;next;
<a name="l00073"></a>00073       te-&gt;timeCurrent -= AT91C_BASE_TC0-&gt;TC_RC + AT91C_BASE_TC0-&gt;TC_CV;
<a name="l00074"></a>00074       <span class="keywordflow">if</span> ( te-&gt;timeCurrent &lt;= 0 )
<a name="l00075"></a>00075       {
<a name="l00076"></a>00076         <span class="keywordflow">if</span> ( te-&gt;repeat )
<a name="l00077"></a>00077         {
<a name="l00078"></a>00078           te-&gt;timeCurrent += te-&gt;timeInitial;
<a name="l00079"></a>00079         }
<a name="l00080"></a>00080         <span class="keywordflow">else</span>
<a name="l00081"></a>00081         {
<a name="l00082"></a>00082           <span class="comment">// remove it if necessary (do this first!)</span>
<a name="l00083"></a>00083           <span class="keywordflow">if</span> ( Timer.previous == NULL )
<a name="l00084"></a>00084             Timer.first = Timer.next;
<a name="l00085"></a>00085           <span class="keywordflow">else</span>
<a name="l00086"></a>00086             Timer.previous-&gt;next = Timer.next;     
<a name="l00087"></a>00087         }
<a name="l00088"></a>00088 
<a name="l00089"></a>00089         <span class="keywordflow">if</span> ( te-&gt;callback != NULL )
<a name="l00090"></a>00090         {
<a name="l00091"></a>00091           <span class="comment">// in this callback, the callee is free to add and remove any members of this list</span>
<a name="l00092"></a>00092           <span class="comment">// which might effect the first, next and previous pointers</span>
<a name="l00093"></a>00093           <span class="comment">// so don't assume any of those local variables are good anymore</span>
<a name="l00094"></a>00094           (*te-&gt;callback)( te-&gt;id );
<a name="l00095"></a>00095         }
<a name="l00096"></a>00096 
<a name="l00097"></a>00097         <span class="comment">// Assuming we're still on the list (if we were removed, then re-added, we'd be on the beggining of</span>
<a name="l00098"></a>00098         <span class="comment">// the list with this task already performed) see whether our time is the next to run</span>
<a name="l00099"></a>00099         <span class="keywordflow">if</span> ( ( Timer.previous == NULL &amp;&amp; Timer.first == te ) ||
<a name="l00100"></a>00100              ( Timer.previous != NULL &amp;&amp; Timer.previous-&gt;next == te ) )
<a name="l00101"></a>00101         {
<a name="l00102"></a>00102           <span class="keywordflow">if</span> ( Timer.nextTime == -1 || te-&gt;timeCurrent &lt; Timer.nextTime )
<a name="l00103"></a>00103             Timer.nextTime = te-&gt;timeCurrent;
<a name="l00104"></a>00104         }
<a name="l00105"></a>00105       } 
<a name="l00106"></a>00106       <span class="keywordflow">else</span>
<a name="l00107"></a>00107       {
<a name="l00108"></a>00108         Timer.previous = te;
<a name="l00109"></a>00109       }
<a name="l00110"></a>00110 
<a name="l00111"></a>00111       te = Timer.next;
<a name="l00112"></a>00112     }
<a name="l00113"></a>00113 
<a name="l00114"></a>00114     <span class="keywordflow">if</span> ( Timer.first != NULL )
<a name="l00115"></a>00115     {
<a name="l00116"></a>00116       <span class="comment">// Add in whatever we're at now</span>
<a name="l00117"></a>00117       Timer.nextTime += AT91C_BASE_TC0-&gt;TC_CV;
<a name="l00118"></a>00118       <span class="comment">// Make sure it's not too big</span>
<a name="l00119"></a>00119       <span class="keywordflow">if</span> ( Timer.nextTime &gt; 0xFFFF )
<a name="l00120"></a>00120         Timer.nextTime = 0xFFFF;
<a name="l00121"></a>00121       AT91C_BASE_TC0-&gt;TC_RC = Timer.nextTime;
<a name="l00122"></a>00122     }
<a name="l00123"></a>00123     <span class="keywordflow">else</span>
<a name="l00124"></a>00124     {
<a name="l00125"></a>00125       AT91C_BASE_TC0-&gt;TC_CCR = AT91C_TC_CLKDIS;
<a name="l00126"></a>00126       Timer.running = <span class="keyword">false</span>;
<a name="l00127"></a>00127     }
<a name="l00128"></a>00128 
<a name="l00129"></a>00129     jitter = AT91C_BASE_TC0-&gt;TC_CV;
<a name="l00130"></a>00130 
<a name="l00131"></a>00131     Timer.servicing = <span class="keyword">false</span>;
<a name="l00132"></a>00132   }
<a name="l00133"></a>00133 
<a name="l00134"></a>00134   <span class="comment">/* Clear AIC to complete ISR processing */</span>
<a name="l00135"></a>00135   AT91C_BASE_AIC-&gt;AIC_EOICR = 0;
<a name="l00136"></a>00136 
<a name="l00137"></a>00137   <span class="comment">/* Do a task switch if needed */</span>
<a name="l00138"></a>00138   <span class="comment">// portEXIT_SWITCHING_ISR( false );</span>
<a name="l00139"></a>00139 }
<a name="l00140"></a>00140 
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  <p class="footer">The Make Controller Kit is an open source project maintained by <a href="http://www.makingthings.com">MakingThings</a>.<br />
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		This document was last updated on 5 Dec 2007.
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